As pointed out by David G above, possibly because it doesn't work if there is no comma. The OP may have implied that the string would always have a comma, but in many instances the delimiter is not guaranteed. See jsfiddle.net/13pkp1xn
– Bumptious Q BangwhistleJan 23 '17 at 10:51

Using array deconstruction, you could do: const [streetAddress,] = addy.split(','); This is helpful for cases when you want more than one value, such as: let [callerIdName, callerId] = callerIdString.split('<'); (original callerIdString format is MCMULLIN,PARKER <+1XXXXXXXXXX>)
– GoogleMacAug 31 '18 at 22:37